(1) Field of the Invention
The invention relates to submarine countermeasure assemblies and is directed more particularly to a propeller protector for mounting on a countermeasure vehicle.
(2) Description of the Prior Art
In FIG. 1, there is shown a typical submarine countermeasure apparatus 20. The apparatus 20 includes a launch tube 22 which, in operation, is disposed outboard of the submarine pressure hull (not shown). A countermeasure vehicle 24 is housed in the launch tube 22 and includes an array assembly 26 and a tailcone assembly 28. The tailcone assembly 28 includes an annular shield 27 surrounding a propulsion propeller 29 (FIG. 2). The array assembly 26 is protected by a surrounding sabot 30. Disposed in the launch tube 22 is a ram plate 32 and a gas generator 34. The launch tube is closed by a forward tube cover 36 and an after tube cover 38.
In operation, the gas generator 34 is activated by an electrical pulse from the submarine fire control system and generates sufficient gas pressure to move the ram plate 32 forwardly. The ram plate 32 pushes the countermeasure vehicle 24 forwardly, breaking away the forward tube cover 36 and launching the countermeasure vehicle 24 from the launch tube 22. In due course, the sabot 30 disengages from around the array assembly 26 and the array assembly is activated to emit acoustic signals.
It has been found that upon launch of the countermeasure vehicle 24, the tailcone assembly 28, and particularly the propeller 29 of the countermeasure vehicle 24, is sometimes subjected to substantial bending moments which result in propeller damage and deployment failure. The ram plate 32 pushes against the tailcone assembly 28 with a force in thousands of pounds and the bending moments on the countermeasure vehicle propeller 29, caused by water impacting the propeller as it exits the launch tube while the submarine is underway at high speeds, can be in thousands of foot pounds. While providing some protection, the shield 27 is not sufficient to protect the propeller from damage.
Accordingly, there is a need for improved propeller protection which can reduce bending moments.
An object of the invention is, therefore, to provide an improved submarine countermeasure vehicle propeller protector structured for successful launch and deployment under conditions inflicting high bending moments upon the propeller.
With the above and other objects in view, as will hereinafter appear, a feature of the present invention is the provision of a submarine countermeasure propeller protector for a countermeasure vehicle having on an after portion thereof a propeller shaft, a propeller fixed to the shaft, radial fins fixed on an after surface of the vehicle and extending outwardly from the shaft, and a shield fixed to outer edges of the fins and surrounding the propeller. The countermeasure propeller protector comprises a tubular sleeve having an end wall at a first end thereof, and an open second end adapted to be engaged with the vehicle, at least one of the end wall and side walls of the sleeve having perforations therein. The sleeve end wall is provided with a central opening therein. A nut is fixed to the sleeve end wall and is threadedly mounted on the shaft and disposed around the central opening. Stop structure on the sleeve second end and the vehicle prevent rotation of the sleeve relative to the vehicle. Rotation of the propeller shaft unscrews the shaft from the nut, permitting the nut, and thereby the sleeve, to move axially to disengage from the vehicle.